feat: add Docker support and logging enhancements

- Introduced Dockerfile and .dockerignore for containerization of the backend service.
- Added logging configuration with support for daily rolling logs and customizable log levels.
- Enhanced the server to utilize structured logging with zap, including detailed request and error logging.
- Updated configuration to include logging parameters and proxy settings.
- Implemented tests for logging configuration and proxy settings.

backend/Dockerfile

@@ -0,0 +1,23 @@
+FROM golang:1.25-alpine AS builder
+
+WORKDIR /src
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -trimpath -ldflags="-s -w" -o /out/server ./cmd/server
+
+FROM alpine:3.20
+
+RUN addgroup -S app && adduser -S -G app app
+
+WORKDIR /app
+COPY --from=builder /out/server /app/server
+COPY config.example.json /app/config.example.json
+
+ENV PORT=8080
+EXPOSE 8080
+
+USER app
+ENTRYPOINT ["/app/server"]